Jack H-20210618T132625Z-001 (1)
Is Water Wet?
Overview
This lesson includes a lab that has students differentiating between hydrophilic and hydrophobic surfaces and is designed for a 7th-grade science class in Indiana. Teacher-developed resources are attached for student use.
Standards
Indiana 7th Grade:
SEPS.3
6-8.E.2
7.ESS.6
Learning Objective
Students will create a hydrophobic surface using principles of nanotechnology.
Materials
Gallery Walk Displays -- found in this document
Sticky Notes (2 per student)
Lab Report (1 per student) -- found in this document
Lab Protocol -- found in this document
Glass slides (1 per student)
Gloves (1 pair per student)
Face masks (1 per student)
Tape (1” strip per student)
Dropper (Class set, 1 per student)
Water (feel free to use food coloring for added effect!)
Krylon Color Master Clear Spray (1 can per 8 students), or
Arrid XX Spray (1 can per 8 students), or
Sigma Coat
Background
Teacher Information/Concepts:
Scientists are always trying to find ways to use technology to mimic features found naturally in nature that could be advantages to our lives.
Nano refers to any substance 1 - 100 nanometers in size.
Hydrophobic surfaces repel water and are waterproof.
We can manipulate the surface of a substance using nanotechnology.
Prior Student Knowledge:
Atoms can interact in a variety of ways to create molecules with distinctive properties.
A meniscus is formed because of the polarity of water.
Possible Preconceptions/Misconceptions:
If students struggle to grasp the concept of hydrophobic and hydrophilic, use an oil and water demonstration. The visualization of how water will not remove oil but dish soap will help students make the connection to the real world.
In addition, if students struggle to understand how hydrophobic/philic materials interact draw a diagram of how molecule of dish soap interact with oil to remove them. The hydrophobic attaches to the oil which is also hydrophobic while the hydrophilic part attaches to the water, essentially creating a soluble substance.
Procedure
Vocabulary: Biomimicry, Nanotechnology, Hydrophobic, Hydrophilic, Ambiphilic |
Hook/Set the Stage: Engage prior learning
Do Now/Gallery Walk: When students walk in they will pick up two sticky notes. When class begins have students walk around the room silently for 5 minutes examining the different displays. There will be laminated papers around the room with examples of biomimicry. Students will write their names on the sticky notes and leave them next to the two examples they find most interesting.
++Displays (first attachment): Lotus Leaf (self-cleaning and repels water), Jellyfish (bioluminescence), Humpback Whales (efficient wind energy), Mosquitos (needles), Dolphins (underwater signals)
After 5 minutes, all students should return to their seats. Discuss which organisms have the most or least sticky notes - why are those properties more or less desirable? Be sure to end the class discussion with the lotus leaf.
Demonstration: Show a pair of Jordans (shoes) to the class that has been pretreated with a hydrophobic coating. Discuss with the class what will happen if you were to pour water or another liquid on it. Pour some water on a towel and have students feel it - is it wet? After confirming that the water will make the cloth object wet, pour water on the shoe. Have some students touch it - is it wet? Discuss WHY the shoe did not get wet. If time allows also demonstrate by pouring some sort of juice or colored water.
Investigate: Examine phenomena/activities/simulations/instruction
While explaining the demonstration, write up the words Nanotechnology, Hydrophobic, Hydrophilic, Ambiphile on the board. Breakdown each word into their root words “Nano,” “Technology,” “Hydro,” “Phobic,” “Phillic/Phile,” and “Ambi”
After breaking down the compounds of each word start by talking about the real world applications of creating something that is waterproof. Have students pair up to brainstorm a list of ideas (longest list wins)! Have the students all stand up and go from group to group each sharing a unique idea. When a group is out of original ideas they sit down.
Next, explain that we will be creating a waterproof object using nanotechnology. To put this size in perspective, show either one of these videos: (https://www.youtube.com/watch?v=IC3AcItKc3U) (https://www.youtube.com/watch?v=uaGEjrADGPA)
Each student will receive a glass slide, gloves, and face masks.
Referenced lab guidelines (suggested ones at the end of this document, feel free to use your own )
Students should follow this procedure:
- Apply the tape to the glass slide on one side, this will be your non coated side
- Spray the Krylon Color Master Clear on the glass slide
- Spray the the Arrid XX Spray on the glass slide
- Let dry for 10 minutes (answer any questions, example lab report is HERE)
- Remove tape
- Use a dropper to apply some water to the slide
- Put away the sprays, throw away all disposables (gloves, masks, tape, etc.)
Facilitate a post lab discussion with these guiding questions:
- Why was the area of the glass that had been covered in tape, not hydrophobic?
- Why would this method of creating a hydrophobic surface not be good for other glass surfaces like car windows or rearview mirrors?
- How did we create a hydrophobic substance?
STEM Differentiation & Integration:
There are three distinct ways this activity can be adjusted based on limited materials, content, or other accommodations.
- The activity can be done in groups if materials are limited. Groups of 2 or groups of 4
- To explore more of the math, you can discuss the angles required for a hydrophobic, superhydrophobic, or hydrophilic surface.
- Consider having a few copies of the lab report with sentence starters.
Assessment Strategies:
Before this class period, students have already completed the official NSF pre-assessment.
Slides will be evaluated based on their ability to repel water.
Lab Reports will be collected to evaluate learning as it relates to this objective.
The next day, an NSF post-assessment will be given as a take-home assessment.
Credits
This learning module was created by Jack Hesser, a participant in Indiana University-Purdue University’s NSF-Funded “Nanotechnology Experiences for Students and Teachers (NEST)” Program (Award # 1513112).